Third Dorsal Interosseous Muscle Anatomy
Origin: Third and fourth metacarpals
Insertion: Dorsal extensor expansion (extensor aponeurosis)
Innervation: Cervical roots): C8-T1
Nerve: Ulnar Nerve ( deep ulnar motor branch)
- The dorsal interosseous muscles are bipennate muscles located between the metacarpals.
- The first dorsal interosseous muscle inserts into the index proximal phalanx while the 2nd, 3rd, and 4th interossei insert into bone and the extensor aponeurosis.
- The dorsal interosseous muscles abduct the fingers, flex the MP joints, and extend the PIP and DIP joints.
- The interossei muscles are in the deepest layer of hand muscles and contained in a strong fascial compartment.
Diagrams & Photos
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Note Third Dorsal Interosseous Muscle -
Third Dorsal Interosseous Muscle (arrow)
Key Points
- The dorsal interosseous muscles pass dorsal to the deep interosseous ligament but volar to the MP joint axis of motion.
- The interossei muscles can be damaged by increased compartment pressures associated with intrinsic compartment syndrome.
- Contracted dorsal interosseous muscles can lead to intrinsic tightness that limits active finger flexion.